<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        
    </style>
</head>
<body>
    <div class="box"></div>
</body>
<script>

    var box = document.querySelector(".box")

    console.log(box);
    console.log(typeof box);

    box.abc = "hello";

    box.innerHTML
    box.id
    box.children

    console.log(box.abc);
    console.log(box.class);
    console.log(box.className);
    console.log(box.tagName);
    
</script>
</html>